Celestial Navigation (instruction video)

> Military solutions will fall back to inertial, celestial or optical guidance, and people using GPS for navigation will at worst show up where they need to be somewhat later than planned. The US Navy re-started celestial navigation a few years ago: * [LINK] This (1960s?) US government produced (45m) video video gives a pretty good overview: * [VIDEO] For those wanting to invest (substantially) more time, the two videos by "Tippecanoe Boats" are slightly rambling at times, but he does lay things out pretty well by the end of it (second is largely examples): * [LINK] * [LINK]

Yeah, what is it about these old military materials that makes them so great? They're easy to follow and understand. Here's an old video about celestial navigation: [VIDEO] It feels like we've forgotten how to make videos like these.

> I'd think that the Earth rotating would be obvious much, much sooner […] How exactly could you tell the difference between one moving reference and another? Einstein eventually showed us that it is not possible. As this US Navy video shows, having the Earth stand still and having the 'celestial sphere' move actually makes celestial navigation using a sextant possible / mathematically easy: * [VIDEO] / [LINK] The Ancients / pre-Moderns concluded that the stars were on one celestial sphere and the wanderers ( planetes in Greek) were on others.

Training for this was discontinued, but brought back in 2016: * [LINK] Now if only the US (and others) would get their act together and build out a backup system to GNSS. China, for example, has built out an eLoran system: * [LINK] An old USAF video explaining how the theory works (it assumes a geocentric worldview: the Earth is the centre of the universe (but it's not flat :)): * [VIDEO]

> Curious how navigation at night was not possible without expensive equipment, sounds like they were relying only on starts in the morning and evening? As a sibling comment notes, it is possible. There are tables for lunar distance: * [LINK] * [LINK] * [LINK] The planets Venus, Mars, Jupiter, and Saturn can be used, as well as several dozen planets (lookup tables in an almanac) * [LINK] * [LINK] Two US military videos explaining the theory (ground points/GP, circle of position, etc ): * USAF: [VIDEO] * Army: [LINK] The USAF has a video because that's how planes used to do navigation outside of radio range—sextants on the ceiling of the cockpit: * [LINK] * [LINK]

I love these military training movies, they're so good at teaching complex concepts. This one about celestial navigation is really good as well: [VIDEO]